我在A公司的perm 申请出了点问题，B公司给了offer，并且说我上班后马上给我办perm。请问：
1. 如果我已经开始在B公司上班，而且B公司的h1b transfer petition 也被批准，我在等B公司perm的时候，还可以回A公司吗？
-Yes if A Company have not requested USCIS to revoke/cancel your H-1 status yet.
2. B公司的petition一通过，A公司的 original h1b 就自动作废了吗？
-No. But by immigration law, A compnay will request USCIS to revoke your H-1 status sponsored by them, which of course does not affect your status to work for B Company.
3. A和B可以同时给同一个外籍劳工办理perm吗？
-Yes. But the problem is that one of the compnanies will be angry because the company cost a lot of money (filing fee, lawyer fee,etc.) and energy to do the H-1 and PERM petitions for you. Then, you will not work for them after they do the H-1 and PERM for you, and they have to find anther person to file the position which takes time and enery also.
